But the irregularity of their form has still greater effect on the draught of the ice. There- 

 fore, if the floe has flat and wide underwater parts, its narrow above-water part can rise consider- 

 ably above the level of the sea. This phenomenon is particularly frequent with icebergs destroyed 

 by melting, which adopt extremely fantastic forms during this period. Thus, according to Smith, 

 the relation of the draught of icebergs to their elevation above sea level is equal, on an average, to 

 the amounts shovra in table 27. 



TABLE 27. THE RELATION OF THE DRAUGHT 

 TO THE HEIGHT OF THE ABOVE- 

 WATER PART OF ICEBERGS OF 

 VARIOUS FORMS 



Table top icebergs 5 



Rounded icebergs 4 



Pyramidal icebergs 3 



Columnar icebergs 2 



Winged icebergs 1 



These results are based on numerous direct measurements of the heights and draught of ice- 

 bergs which were carried out by the International Ice Patrol, and also according to the observa- 

 tional data of many expeditions. 



The course of meltage and destruction of icebergs is extremely characteristic. It is, how- 

 ever, necessary to differentiate between the wastage or destruction of icebergs in the areas of their 

 formation and in the areas to which they have been carried. These processes have been studied 

 best in the areas of the Labrador Current and the Gulf Stream. 



According to Smith, during the summer, water in the Labrador Current is cold and the air is 

 warm; because of this the above-water part of the iceberg melts first of all. But in the Gulf Stream, 

 during the spring, the water is considerably warmer than the air, as a result the underwater part 

 melts and is destroyed faster. 



Melting reaches its greatest rate during the summer in the Gulf Stream (warm air and warm 

 water). Rivulets stream down the iceberg in a constant flow, different pieces and chunks break off 

 from the iceberg now and then, the center of balance is destroyed, and the iceberg frequently turns 

 over. It is natural that the smaller the iceberg, the more rapidly it melts. This is explained not 

 only by the fact that the smaller the iceberg, the greater is the relation of its surface to its size, 

 but also by the fact that the small iceberg floats in the surface layers more, i.e. , the water layers 

 which are more mobile and, during the summer, warmer. 



According to Smith, the height of an iceberg during the summer in Baffin Gulf decreases by 

 . 7 m per day on an average; in Davis Strait, this decrease is up to 1.3 m; in Newfoundland, up to 

 2.0 m; and to the south of the Great Banks, up to 3.3 m per day. In the three months of its journey 

 from Baffin Gulf to the region south of the Great Banks, the average height of an iceberg decreases 

 from 80 to 40 m, and its mass from 1, 500, 000 to 150, 000 tons. 



According to the observations of the Ice Patrol, the height of the icebergs in the Gulf Stream 

 decreases by 10 m per day in separate instances, and in June, 1926, a large iceberg 127 m long 

 melted in 36 hours at the edge of the Gulf Stream. 



130 



